/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkGaussFilter_DEFINED
#define SkGaussFilter_DEFINED

#include <cstddef>

// Define gaussian filters for values of sigma < 2. Produce values good to 1 part in 1,000,000.
// Produces values as defined in "Scale-Space for Discrete Signals" by Tony Lindeberg.
class SkGaussFilter {
public:
    inline static constexpr int kGaussArrayMax = 6;

    explicit SkGaussFilter(double sigma);

    size_t size() const
    {
        return fN;
    }
    int radius() const
    {
        return fN - 1;
    }
    int width() const
    {
        return 2 * this->radius() + 1;
    }

    // Allow a filter to be used in a C++ ranged-for loop.
    const double *begin() const
    {
        return &fBasis[0];
    }
    const double *end() const
    {
        return &fBasis[fN];
    }

private:
    double fBasis[kGaussArrayMax];
    int fN;
};

#endif // SkGaussFilter_DEFINED
